CN111601650B

CN111601650B - Filter system

Info

Publication number: CN111601650B
Application number: CN201980007651.4A
Authority: CN
Inventors: R·本·霍林; K·阿蒂亚斯; A·甄德尔
Original assignee: Amiad Water Systems Ltd
Current assignee: Amiad Water Systems Ltd
Priority date: 2018-01-25
Filing date: 2019-01-22
Publication date: 2022-07-29
Anticipated expiration: 2039-01-22
Also published as: ES2926389T3; EP3743188A4; WO2019145943A1; US11040299B2; ZA202000144B; CL2020001665A1; AU2019211764A1; EP3743188A1; PE20211843A1; EP4088804A1; AU2019211764B2; IL271860A; US20210069619A1; MX2020007518A; BR112020012855A2; IL271860B; EP3743188B1; CN111601650A; IL271860B2

Abstract

A filtration system is disclosed that includes a filter element located within a filtration chamber and a valve arrangement located outside the filtration chamber for reversing the direction of fluid flow through the filter element for backwashing. Thus, the valve device serves as a common valve for both process filtration and backwash. The common valve is based on a linearly movable plug located inside a valve housing which can communicate with the filter chamber, the source of fluid to be filtered and the discharge port for backflushing fluid through three respective openings in the valve housing, and is characterized in that an uninterrupted, non-tortuous flow passage extends at least from outside the inlet opening of the valve housing to the body of the filter element whenever the common valve is in the filtering mode of operation.

Description

Filter system

Cross Reference to Related Applications

This application claims the benefit of provisional patent application No.62/621,934 entitled "filtration system" filed on 25.1.2018, which is incorporated by reference herein in its entirety without causing any objection.

Technical Field

The present disclosure relates generally to the field of filtration systems, and in particular to automatic backwash of filtration systems.

Background

Among the factors that affect the efficiency of a backwash filter system are the amount of liquid (e.g., fresh water in the water filter system) that is wasted when performing backwash. To objectively assess system performance, liquid loss can be measured as a percentage of the total amount of liquid that the system is handling.

Another efficiency factor is the amount of kinetic energy lost by the liquid as it flows between the inlet and outlet of the system during the filtration mode of operation (typically more so during backwash mode). The higher the energy loss, the more powerful the pumping is required to maintain the desired flow rate at the system outlet. Pumping power is expensive in terms of the type of pump used, its power consumption and sometimes also the physical deterioration of the piping components and fittings used under excessive pressure between the pump and the filtration system.

Disclosure of Invention

One exemplary embodiment of the disclosed subject matter is a filtration system comprising: a filtration chamber; a filter element housed within the filter chamber, wherein the filter element comprises a body of the filter element; a common valve comprising a valve housing in fluid communication with the filtration chamber, a source of fluid to be filtered, and a discharge port for backwash fluid through three respective openings in the valve housing, wherein the common valve, the filtration chamber, and a tube segment connected between the common valve and the filtration chamber are collectively configured for: providing an uninterrupted, tortuosity-free flow path extending at least from outside of an inlet opening of the common valve to the body of the filter element whenever the common valve is in a filtration mode of operation.

In some exemplary embodiments, the inlet opening of the common valve may be the outermost opening in the body of the valve housing itself (i.e., after removal of any removable pipe segments that may be connected between the common valve and the source of source fluid).

In various embodiments of the presently disclosed subject matter, a cross-sectional area of the non-tortuous flow passage perpendicular to its longitudinal axis is about 50% or more of an area of the inlet opening of the common valve.

In various embodiments of the presently disclosed subject matter, the common valve includes a plug linearly movable within a central void of the common valve, wherein a rear wall of the plug has a protrusion that substantially fits within a mating retaining recess, wherein the mating retaining recess extends between a discharge outlet formed in a wall of the valve housing and the central void and has an internal free space with a predetermined volume, wherein the protrusion is configured to at least partially occupy the internal free space when the plug transitions between a rearmost position of the plug within the void and a position closer to a forwardmost position of the plug within the void until the protrusion completely exits from within the retaining recess, thereby depending on the extent to which the recess volume is occupied by the rear protrusion, while reducing fluid drainage through the fixed recess during transition of the plug between a filtration mode of operation and a backwash mode of operation.

In various embodiments of the presently disclosed subject matter, the common valve includes a plug linearly movable between a first position and a second position, wherein the first position is associated with a filtration mode of operation, wherein the second position is associated with a backwash mode of operation, wherein the plug includes a rear protrusion configured to restrict passage of fluid from a central void of the valve to the discharge port during linear movement of the plug from the first position to the second position, wherein for at least an initial 30% of a full stroke of the linear movement, at least a portion of a predetermined volume of the recess is occupied by the rear protrusion, thereby reducing fluid wasted through the discharge port according to a degree of the recess volume occupied by the rear protrusion.

In various embodiments of the presently disclosed subject matter, the rear projection is cylindrical, with a height of the rear projection oriented parallel to the direction of the linear motion.

In various embodiments of the presently disclosed subject matter, the common valve includes a plug linearly movable between a first position and a second position, wherein the first position is associated with a filtration mode of operation, wherein the second position is associated with a backwash mode of operation, wherein the plug includes a front protrusion configured to enter the inlet opening to reduce a flow rate of fluid into the inlet opening during linear movement of the plug from the first position to the second position, wherein for at least a last 30% of a full stroke of the linear movement, at least a portion of the front protrusion passes through the inlet opening to reduce fluid waste through the drain port as a function of a degree to which the front protrusion passes through the inlet opening.

In various embodiments of the presently disclosed subject matter, the front projection tapers, e.g., is conical, toward the inlet opening.

In various embodiments of the presently disclosed subject matter, the angle between the longitudinal axis of the tube segment and the longitudinal axis of the filter chamber is 35 to 55 degrees.

In various embodiments of the presently disclosed subject matter, the tube segment has an elliptical cross-section perpendicular to its longitudinal axis, and the cross-section is flat in a direction parallel to the direction of linear motion, such that for a given cross-sectional area of the tube segment, the range of linear motion of the stopper is shortened.

In various embodiments of the presently disclosed subject matter, the proximal end of the filtration chamber, at least a majority of the housing of the common valve, and the tube segment are non-separable members of a single piece of material.

In various embodiments of the presently disclosed subject matter, flow through a first opening in a housing of the filtration chamber enters the chamber during a filtration mode of operation and exits the chamber during a backwash mode of operation, wherein flow through a second opening in the housing of the filtration chamber exits the chamber during the filtration mode of operation and enters the chamber during the backwash mode of operation.

Another exemplary embodiment of the disclosed subject matter is a dual filtration system comprising a first filtration system and a second filtration system each according to the first exemplary embodiment or according to any one of the following variant embodiments. The first and second filtration systems are connected together in a mirror image configuration, with the inlet opening of the common valve in the first filtration system facing the inlet opening of the common valve in the second filtration system and aligned with the inlet opening of the common valve in the second filtration system through a flow diverter of the fluid to be filtered.

In various embodiments of the presently disclosed subject matter, the flow splitter includes a pair of arcuate tubes that diverge from a central common tube.

In various embodiments of the presently disclosed subject matter, the first and second filtration systems are connected together in a mirror image configuration, wherein the outlet opening of the filtration chamber in the first filtration system faces the outlet opening of the filtration chamber in the second filtration system and is aligned with the outlet opening of the filtration chamber in the second filtration system by a flow combiner of filtered fluid.

In various embodiments of the presently disclosed subject matter, the maximum inside bend radius of each of the arcuate tubes is about 100% to 150% of the diameter of the central common tube.

In various embodiments of the presently disclosed subject matter, the internal cross-sectional area of the central common tube of the flow splitter or flow combiner is approximately equal to the internal cross-sectional area of any of the tubes diverging from the central common tube.

One general aspect of the presently disclosed subject matter is a valve apparatus having a linearly movable plug for selecting between first and second flow paths corresponding to first and second extreme positions of the linearly movable plug and constituting a common valve, the valve apparatus comprising: a housing; the stopper being linearly movable within the housing between the first and second extreme positions; a normally open port, the first normally open port being common to the first flow path and the second flow path; a first port having an external opening in fluid communication with the normally-open port when the stopper is in the first limit position; a second port in fluid communication with the normally-open port when the plug is in the second limit position, wherein when the plug is in the first limit position, the fluid communication between the external opening and the normally-open port includes a linear flow path having a cross-sectional area greater than 50% of an area of the external opening, constituting an uninterrupted, non-tortuous flow path from at least an exterior of the external opening to an exterior of the normally-open port.

In various embodiments of the presently disclosed subject matter, the cross-sectional area of the linear flow path is greater than 75% of the area of the external opening.

In various embodiments of the presently disclosed subject matter, the normally-open port has a predetermined open area in a plane parallel to a direction of linear movement of the stopper, wherein the open area has a minor axis in the plane defining a width of a bidirectional port and a major axis in the plane defining a length of the bidirectional port, wherein the width is less than the length, wherein the minor axis in the plane and the width of the respective bidirectional port are parallel or nearly parallel to the direction of movement of the stopper.

In various embodiments of the presently disclosed subject matter, the rear wall of the plug has a protrusion that substantially fits within a mating retaining recess, wherein the mating retaining recess extends between the second port and a central void of the valve device, wherein the protrusion is configured to prevent or substantially restrict the flow of fluid from the central void to the second port when the plug transitions between a rearmost position within the void and a position substantially proximate its forwardmost position within the void, wherein the rearmost position may be associated with a filter mode of operation of a self-cleaning filter system, wherein the forwardmost position may be associated with a backwash mode of operation of the self-cleaning filter system, such that during a change mode of operation of the plug from the filter mode to the backwash mode of operation once the plug is configured, allowing for reduced liquid discharge.

In various embodiments of the presently disclosed subject matter, the first extreme position may be associated with a filtration mode of operation of a self-cleaning filtration system, wherein the second extreme position may be associated with a back flush mode of operation of the self-cleaning filtration system, wherein the plug comprises a front protrusion configured to enter the external opening such that for at least a last 30% of a full range of linear motion of the plug between the first extreme position and the second extreme position, a flow rate of fluid entering the first port is reduced during linear motion of the plug from the first extreme position to the second extreme position, thereby reducing fluid wasted through the second port depending on a degree to which the front protrusion penetrates the external opening.

In various embodiments of the presently disclosed subject matter, the rear wall of the plug has a protrusion that substantially fits within a mating retaining recess, wherein the mating retaining recess extends between the second port and a central void of the valve device, wherein the protrusion is configured to block or substantially restrict fluid flow from the central void to the second port during transition of the plug between a rearmost position within the void and a forwardmost position substantially proximate thereto within the void; wherein the stopper further comprises a front protrusion configured to enter the external opening to reduce a flow of fluid into the first port during linear movement of the stopper from the first extreme position to the second extreme position for at least a last 30% of a full range of linear movement of the stopper between the first extreme position and the second extreme position; and wherein said rearmost position may be associated with a filter mode of operation of a self-cleaning filter system, wherein said frontmost position may be associated with a backwash mode of operation of said self-cleaning filter system, thereby allowing for reduced liquid drainage depending on the extent to which the volume of the recess is occupied by the rear projection and the extent to which the front projection passes through the external opening during a change mode of operation of the plug once configured from the filter mode of operation to the backwash mode of operation

In various embodiments of the presently disclosed subject matter, wherein the rear projection occupies a volume of the recess or the front projection penetrates the exterior opening for at least 50% of a full range of linear movement of the stopper between the first and second extreme positions.

In various embodiments of the presently disclosed subject matter, wherein a distance between a front end of the front projection and a rear end of the rear projection is greater than 80% of a distance between a front end of the recess and the exterior opening.

In various embodiments of the present invention, a distance between a front end of the front protrusion and a rear end of the rear protrusion is equal to or greater than a distance between a front end of the recess and the external opening.

Another general aspect of the presently disclosed subject matter is a filtration system component comprising, in an inseparable single piece: a portion of the filtration chamber housing, a portion of the common valve housing located outside and distal from the portion of the filtration chamber housing, and a tube segment connected between the portion of the filtration chamber housing and the portion of the common valve housing, wherein the portion of the filtration chamber housing, the portion of the common valve housing, and the tube segment are collectively configured for: providing an uninterrupted unbent fluid passage extending at least from outside the inlet opening of the common valve to inside the portion of the filtration chamber housing.

Drawings

The subject matter of the present disclosure will be understood and appreciated more fully from the following detailed description taken in conjunction with the accompanying drawings, in which corresponding or like numerals or characters indicate corresponding or like parts. Unless otherwise indicated, the drawings provide exemplary embodiments or aspects of the disclosure, and do not limit the scope of the disclosure. In the drawings:

figure 1A illustrates a cross-sectional view of a pair of automatic backflush filter assemblies shown operating in a mirror image configuration during a filtration-only mode of operation according to the subject matter of the present disclosure.

FIG. 1B shows the left half of the pair of assemblies of FIG. 1A in a transition state from a filtration mode of operation to a backwash mode of operation.

FIG. 1C shows the pair of assemblies of FIG. 1A during a backwash mode of operation wherein the filter elements of the left assembly are flushed by a reverse flow of filtered liquid supplied from the right assembly.

FIG. 1D shows an enlarged view of the plug of the common valve taken from the filter assembly of FIG. 1A.

Fig. 1E shows an annotated illustrative view of a core unit of a housing of a filtration assembly according to the subject matter of the present disclosure.

Detailed Description

In view of the foregoing, one of the objectives disclosed below is to provide guidance on how to construct a filtration system that will be more efficient than the similar state of the art systems using similar filtration elements in two respects: the amount of liquid wasted for cleaning the filter, and the amount of kinetic energy lost by the liquid flowing between the inlet and outlet of the system during the filtration mode of operation (such losses are typically exacerbated during the backwash process). The energy loss through the filtration system is related to the hydraulic pressure drop between the inlet and outlet of the system.

During the backwash process, there is typically a temporary drop in liquid pressure at the outlet of the backwash filter system (and, in addition, periodically during the pure filtration mode of operation), due to the fact that the real-time cleaning of the filter is taken from the normal filtration capacity of the system, and also due to the fact that the system consumes a portion of its output for rinsing.

Accordingly, one of the objectives of the present disclosure is to reduce the pressure drop between the inlet and outlet of the filtration system in both modes of operation and to reduce its severity during the backwash process.

Other objects will become apparent from the description of the disclosed embodiments and the accompanying drawings.

Some of the amount of kinetic energy lost to the body of liquid flowing through the automatic backwash filter is caused by the valve arrangement. Valve means may be required in an automatic backflush filter to direct liquid through the system in the appropriate direction based on the currently anticipated mode of operation (filtration or backflush). For filtration, the valve assembly directs unfiltered liquid from the inlet of the filter, through the filter elements of the filter, and to the outlet of the filter. For backwash, the valve means reverses the flow of liquid through the filter element of the filter by directing the cleaning liquid from the outlet through the filter element which is subjected to the cleaning process by backwash to the dirty liquid drain outlet.

Thus, one problem associated with backwash filter systems is the pressure loss associated with the valve arrangement of the system.

Another problem associated with backflush filter systems is liquid loss during the backflush process.

It is an object of the presently disclosed subject matter to reduce pressure loss between the inlet and outlet of an automatic backflush filter as compared to pressure loss across a replacement backflush filter. In this context, a replacement backflush filter is an automatic backflush filter having the same filter elements and operating under similar external conditions, absent the solution of the present disclosure.

It is another object of the presently disclosed subject matter to reduce the amount of liquid wasted for performing an automatic filter cleaning process.

Some of the solutions disclosed hereinafter may reduce the losses normally associated with both problems.

The drain valve may be used to provide said reversal in the direction of fluid flow through the backflush filter during its flushing mode to the automatic backflush filter. At the same time, the flow of the raw fluid to be filtered through the filter for backwashing may be stopped by the main flow valve. The discharge valve and the main flow valve may be combined into a single valve device, also referred to as a "common valve", which is a valve common for controlling backwash and main flow. A first solution according to the subject matter of the present disclosure aims at reducing the resistance to the liquid flow on the path to be followed by the body of fluid from outside the inlet opening for the raw fluid of the common valve to the body of the filter element.

One general aspect of the presently disclosed subject matter relates to a valve apparatus having a linearly movable plug for selecting between first and second flow paths corresponding to first and second extreme positions of the linearly movable plug, and constituting a common valve. According to the subject matter of the present disclosure, a valve apparatus includes a housing; a stopper linearly movable within the housing between said first and second extreme positions; a normally open port common to the first flow path and the second flow path; a first port having an external opening in fluid communication with the normally-open port when the stopper is in a first limit position; a second port in fluid communication with the normally-open port when the plug is in the second limit position, wherein the fluid communication between the external opening and the normally-open port when the plug is in the first limit position includes a linear flow path having a cross-sectional area greater than 50% of the area of the external opening constituting an uninterrupted, non-tortuous flow path extending at least from the exterior of the external opening to the exterior of the normally-open port.

The valve apparatus according to the broad aspect may be used in any desired industrial application where a linearly movable plug may be preferred for selecting between a first flow path and a second flow path through a normally open port and may accept partial fluid communication between the first flow path and the second flow path when the plug is shifted. The valve device is particularly useful for the following filtration systems: in the filtration system, cleaning of the filter is accomplished by a hydraulic mechanism configured to backwash the filter media.

In various embodiments of the presently disclosed subject matter, the filter media is a disc filter, media filter, or the like. However, the disclosed subject matter is not limited to a particular type of filter element. Any filtration or screening technique of filtration and screening devices may be used.

In one exemplary embodiment of the disclosed subject matter, the filter element is coupled to a bottom end of the housing of the filter chamber, which bottom end constitutes a proximal portion of the filter chamber. The pressurized liquid to be filtered is supplied to the filter chamber from a bi-directional port of the common valve. The bi-directional port functions as an outlet of the common valve during the filtration mode of operation and as an inlet of the common valve during the backwash process. In various embodiments of the disclosed subject matter, the solution comprises: during a filtration mode of operation, the common valve, the housing of the chamber, and the tubing connected therebetween are collectively configured to provide an uninterrupted, torturous flow path extending at least from outside of the inlet opening of the common valve, through the bi-directional port of the valve, and to the body of the filter element. Thus, the common valve may have a particular design to provide an uninterrupted, non-tortuous fluid path from its inlet opening to its bidirectional port. In various embodiments of the disclosed subject matter, the inlet opening of the common valve is an opening at the interface end of the common valve housing through which the common valve may be coupled with a source of fluid to be filtered. In various embodiments of the disclosed subject matter, the bi-directional port of the common valve may be an opening at the interface end of the valve housing through which the valve housing may be coupled or integrated with the tube segment to provide an uninterrupted torturous flow channel portion from the bi-directional port to the opening of the filter chamber facing the filter element, wherein the longitudinal axis of the uninterrupted torturous flow channel portion is substantially overlapping in direction (i.e., does not deviate by more than 15 degrees) with the longitudinal axis of the uninterrupted torturous fluid path through the common valve. Thus, liquid may flow directly from before the common valve to the filter element during the filtration mode of operation, thereby minimizing kinetic energy losses along that portion of the flow from the inlet to the outlet of the filtration system.

In various embodiments, the cross-sectional area of the non-tortuous flow passage perpendicular to its longitudinal axis is about 50% or more of the area of only the inlet opening of the common valve. In some embodiments, the cross-sectional area of the non-tortuous flow passage perpendicular to its longitudinal axis is greater than about 75% of the area of the inlet opening only of the common valve.

In various embodiments, the housing of the chamber, the hollow body of the common valve in which the inlet opening and the bi-directional port are formed, and the tube for providing fluid communication between the housing of the chamber and the bi-directional port are all formed as non-separable members of a single piece of material that constitutes the core unit of the backwash filter unit according to the presently disclosed subject matter

In some embodiments of the disclosed subject matter, the core unit structure is configured without handedness, thus allowing the filtration system to be mirror symmetric, with the same core unit structure being used on either side of the dual filtration assembly.

In various embodiments of the presently disclosed subject matter, the common valve comprises a hydraulic or pneumatic piston-driven plug, wherein a rear wall of the plug facing the piston has a protrusion that fits substantially within a mating recess (wherein the substantially fit is such that when the protrusion is within the recess, the cross-sectional area of the protrusion is greater than 70% of the cross-sectional area of the recess, preferably 95% to 99.9% of the cross-sectional area of the recess, and the two cross-sectional areas share a common plane within the recess that is transverse to the direction of linear movement of the plug), wherein the recess extends between a discharge outlet formed in the valve wall and a central void of the valve, wherein the rear wall protrusion blocks or substantially restricts the flow of liquid from the central void to the discharge outlet when the plug is driven by the piston to transition between its rearmost position within the void and substantially near its forwardmost position within the void, thereby minimizing liquid drainage during the transition of the plug between the filtration mode of operation and the backwash mode of operation.

In various embodiments of the presently disclosed subject matter, the common valve includes a hydraulic or pneumatic piston driven plug, wherein a front wall of the plug facing away from the piston includes a protrusion that protrudes away from the plunger, the protrusion protruding through the inlet opening of the valve as the plug is closer to its forwardmost position, thereby minimizing liquid ingress through the inlet immediately prior to full occlusion. In some embodiments, the projection has a conical shape to minimize interference with the flow of liquid through the valve during the filtration mode of operation.

Fig. 1A to 1C show three lateral cross-sectional views of an exemplary embodiment of a backflush filtration double unit 100 (also referred to as a double filtration assembly) in three different operating states, respectively. The three figures therefore differ in the position of the piston-driven plug wall of the common valve 102 of the left-hand filter assembly, and the resultant direction of liquid flow through the unit, as indicated by the corresponding arrows shown within the tubes and valves involved.

In various embodiments, the backwash filter bi-unit 100 is provided with two identical filter chamber housings (e.g., 110). In the illustrated embodiment, the chambers are positioned in a mirror image configuration and share a common longitudinal axis, with the openings at their proximal ends facing left and

right leg sections

191L and 191R, respectively, of the T or Y fitting making up flow combiner 190, and the proximal ends coupled to left and

right leg sections

191L and 191R, respectively, of the T or Y fitting making up flow combiner 190, with the center tube 191 of the flow combiner making up the outlet tube of backwash filter double unit 100.

It should be noted, however, that some solutions according to the subject matter of the present disclosure do not require backflush filter assemblies and/or have the filter chambers of each backflush filter assembly to be connected in a mirror image configuration. More specifically, a solution involving the structure of the common valve 102 and any internal components thereof and/or the structure of the core unit 101 and any internal components thereof does not necessarily require: the filter units to which they are directly mounted will be mounted in mirror image relationship with the counterpart filter units with which they cooperate to establish the automatic backwash process.

According to a first broad aspect of the presently disclosed subject matter, reduction of resistance to liquid flow is achieved by providing a valve (also referred to as a "common valve 102") comprising: (i) a hollow body of the common valve 102 having at least a first opening 102a, a second opening 102b and a third opening 102c (labeled in fig. 1E), through which at least the first opening 102a, the second opening 102b and the third opening 102c liquid can flow between the interspace 103 of the body of the common valve 102 and the three respective environments outside the body; (ii) a plunger 135 (also referred to as a "rod" in this disclosure) connected at a first end thereof to a stopper 136, the stopper 136 being movable within the void 103 by the plunger 135 between a forwardmost position (shown in the left-hand assembly of fig. 1C) in which the stopper 136 blocks liquid communication between the void 103 and a first opening (102a) of the at least three openings, and a rearwardmost position (shown in, for example, both assemblies of fig. 1A), in which the stopper 136 blocks liquid communication between the void 103 and a third opening (102C) of the at least three openings; wherein the liquid communication between the void 103 and the second opening (102b) of the at least three openings is not interrupted by the plug 136.

In various embodiments of the disclosed subject matter, the plug 136 includes at least one of a forward facing (front facing) and a rearward facing annular sealing region (labeled 136s in fig. 1D). In various embodiments of the disclosed subject matter, a first opening (102a) of the at least three openings is surrounded by an annular recess (labeled 106 in fig. 1E) contoured to match the forward annular sealing region 136s of the plug.

In the context of the present disclosure, an "inlet" of the common valve is an opening in the housing of the valve that constitutes or corresponds to a first opening 102a through which the valve is in liquid communication with a supply of pressurized liquid to be filtered. The inlet may include a coupling device (not shown) by which the inlet may be releasably coupled to an inlet fitting (e.g., Y-fitting 180).

In the context of the present disclosure, the "outlet" of the common valve is an opening in the housing of the valve constituting or corresponding to the second opening 102b, through which the valve is in liquid communication with a filter element or sieving element, such as a disc filter 150 (also referred to herein as "disc filter element"). The fluid communication between the common valve and the filter element is bi-directional. In some exemplary embodiments, during the backwash process, the fluid flow through the second opening 102b is reversed. Thus, the second outlet 102b of the valve may also be referred to as a "bi-directional port" of the common valve in the context of the present disclosure.

In the context of the present disclosure, the "drain outlet" of the common valve is an opening in the housing of the valve that constitutes or corresponds to the third opening 102c, through which the valve can be in fluid communication with the drain system, or through which the valve is open to atmosphere.

In various embodiments of the disclosed subject matter, the valve includes an annular recess having a profile matching the rearward facing annular sealing region 136s of the plug, the profile being located at the rearmost position of the rear sealing region and configured to engage the rearward facing annular sealing region 136s when the plug 136 is in its rearmost position to seal against the passage of liquid from the void 103 to the discharge outlet 103 c. In the illustrated embodiment, the discharge outlet 103c is blocked by the rear side of the wall of the plug 136, independent of the rearward facing annular sealing region 136s, so that the mating contoured annular recess is not shown in the rearward most position of the plug.

In accordance with a second broad aspect of the presently disclosed subject matter, a reduction in wasted liquid during the transition of the stopper 136 between its rearmost and foremost positions is achieved by providing a ledge (protrusion) on the rearward wall of the stopper 136 that protrudes through the cylindrical recess 104h or opening when the stopper is closer to its rearmost position, which ledge is convex toward the plunger. In various embodiments, the bulge of the rearward facing wall resembles a cylinder or protrusion. In some embodiments, the cylindrical rear protrusion 136R and the plunger 135 share a common axis of symmetry.

In further accordance with the second broad aspect, in various embodiments of the disclosed subject matter, the forward-facing wall of the stopper includes a projection or protrusion (also referred to as forward protrusion 136F) that protrudes away from the plunger 135, the projection protruding through the first opening 102a when the stopper 136 is closer to its forwardmost position.

In various embodiments, the forward protrusion 136F of the forward wall resembles a cone. In some embodiments, the tapered front protrusion 136F and the plunger 135 share a common axis of symmetry.

In various embodiments of the disclosed subject matter, the second opening 102b is connected to the filter chamber by an outlet tube member 114.

In various embodiments of the disclosed subject matter, the hollow body of the common valve 102, the outlet tube member 114, and the body of the filtration chamber (i.e., the chamber housing 110) are formed as an inseparable, single-piece unit 101, also referred to as a "core unit," as shown in fig. 1E. In various embodiments of the disclosed subject matter, a housing 130 having a cylindrical shape is removably attached to the hollow body of the common valve 102 at the service opening 102s of the hollow body. The attachment of the housing 130 may be secured to the open access 102s of the hollow body of the common valve 102 by any acceptable coupling means. In some embodiments, the attachment between the hollow body of the common valve 102 and the housing 130 is by means of a coupling clamp. In other embodiments, the connection may be by flanges bolted to each other, or by threaded connections to each other. In various embodiments of the disclosed subject matter, the main body of the filtration chamber has an access opening 113, the access opening 113 of the main body of the filtration chamber being removably covered by the housing cover 120 of the chamber.

In various embodiments of the disclosed subject matter, the longitudinal axis 115 of the outlet tube member 114 forms an angle of 35 degrees to 55 degrees with the longitudinal axis 111 of the filtration chamber.

In some embodiments of the disclosed subject matter, the longitudinal axis 115 of the outlet tube member 114 forms an angle of about 45 degrees with the longitudinal axis 111 of the filtration chamber.

In the present disclosure, when referring to the angle between the longitudinal axis 115 of the outlet tube member 114 and the longitudinal axis 111 of the filtration chamber, the angle referred to is the acute angle between the axes that is closer to the open proximal end 112 of the chamber housing 110, i.e. (in embodiments where the axes are parallel to the respective wall portions), the angle between the axes is equal to and parallel to the angle between the walls of the chamber housing 110 and the outlet tube member 114, as indicated by the curved arrow 188.

Referring again to the first broad aspect, in various embodiments of the disclosed subject matter, the first and

second openings

102a, 102b of the filtration chamber housing 110 and the common valve 102 are arranged such that an uninterrupted, non-tortuous flow path (shown in fig. 1E by arrows 116 between the parallel dashed lines) passes through all of these, thereby minimizing directional changes and turbulence of the body of liquid flowing from outside the first opening 102a to the chamber housing 110.

In various embodiments of the disclosed subject matter, the cross-sectional area of the flow channel 116 measured transverse to the axis 115 and defined by parallel lines of sight extending further from each other between the filter (filter element) 150 and the outside of the first opening 102a is 75% or greater of the cross-sectional area of the outlet tube member 114.

In various embodiments of the disclosed subject matter, the flow channel 116 is substantially parallel to the longitudinal axis 115 of the outlet tube member 114.

In various embodiments of the disclosed subject matter, the cross-section of the outlet tube member 114 transverse to its axis 115 is substantially elliptical. In various embodiments, the cross-section of the outlet duct member 114 transverse to its axis 115 is longer in a direction perpendicular to the plane of the drawing than in a direction parallel to the plane of the drawing (e.g. due to ovality of the cross-section), thereby allowing the stroke of the piston 134 to be shortened and thus the distance between the two extreme positions of the plug 136 to be shortened for a given cross-sectional area of the outlet duct member 114. This may reduce the time required to switch the plug between filtration and cleaning processes and further reduce the liquid loss associated with the switch.

In various embodiments of the disclosed subject matter, the internal cross-sectional area of the common inlet tube section 181 is substantially equal to the internal cross-sectional area of any of the left and

right tube sections

181L, 181R that branch therefrom, measured transverse to the respective intended liquid flow direction.

In various embodiments of the disclosed subject matter, the

tube sections

181L and 181R are arcuate. In some embodiments, its maximum inner bend radius (labeled 181c in fig. 1B) is about 100% to 150% of the diameter of the tube 181. In various embodiments of the disclosed subject matter, the first opening 102a is connected by an inlet pipe member 181 to an inlet fitting (e.g., flange) configured for connection (e.g., by bolts) to a mating outlet fitting (not shown) of a main pipe from which pressurized liquid may be supplied to the filter chamber housing 110 through the valve 102.

Since the degree of labyrinth of the path followed by the liquid body from the inlet pipe to the outlet pipe of the automatic backwashing filter system of the present disclosure is lower compared to the path followed by the liquid body of a competitive system with a valve arrangement lacking the solution of the present disclosure, the pressure loss between the liquid inlet 181i and the liquid outlet 191e of the double unit 100 according to the subject matter of the present disclosure will be reduced, thereby minimizing the overall liquid pressure drop reduction over the filter system comprising the set of double units 100.

The backflush filter unit includes a pair of automatic backflush filter assemblies connected in a mirror image configuration. Each assembly includes a filtration chamber formed by a proximal chamber housing 110 and a cap 120.

The chamber housing 110 and its cover 120 may be secured together by any acceptable coupling means that allows for easy removal of the cover (e.g., for servicing purposes). In some embodiments, they are secured together by a coupling clamp and its specified washer.

Referring now in more detail to the operation of the dual unit 100, a disc filter element 150 is secured within the chamber to the bottom end of the chamber housing 110. The chamber housing 110 is in fluid communication with the common valve through a beveled outlet tube member 114.

The common valve includes a hollow body of the common valve 102 and a piston-driven plug 136 connected to the piston 134 by a piston rod (e.g., a plunger 135). The piston is movable through a housing 130 of the piston due to fluid pressure changes inside the cylinder. Fluid for the control piston (and thus the control plug) is communicated to the cylinder from an external fluid source (not shown) through the control port 131.

In some embodiments, the fluid used to control the piston is a filtered type of liquid and is supplied after filtration, for example, by a secondary filter (not shown), while the desired pressure is achieved by a controller activated pressure booster (not shown).

The female bushing 104 has a bore for a piston rod (e.g., plunger 135) and is secured between the valve void 103 and the housing 130 to isolate therebetween to prevent fluid exchange.

The forward end of the recessed liner 104 (and in various other embodiments, an additional liner located adjacent the first liner) cooperates with the plug 136 to prevent liquid from leaking from the void 103 to the discharge outlet 103 c. In the illustrated embodiment, the recessed liner 104 has a cylindrical recess 104h having a cylindrical shape and configured to receive a mating cylindrical extension (also referred to as a rear protrusion 136R) protruding from the rear wall of the plug 136. Which opens into a discharge opening formed in the hollow body of the common valve 102. Thus, liquid communication will be provided from the void 103 of the valve to the discharge opening through the cylindrical recess 104h each time the cylindrical extension leaves the recess, i.e. at the final stage and more intensively upon completion of the piston stroke driving the plug 136 towards its forwardmost position.

In fig. 1A, the plugs 136 of both the right and left filter assembly valves are in their rearmost positions so that both assemblies operate in the filtering mode. Pressurized liquid enters the dual cell 100 through an inlet 181i of a main pipe section 181 of a T-or Y-splitter 180 (also commonly referred to as a T/Y fitting). The liquid flow is split into mirror image assemblies by

side tube segments

181R and 181L, respectively, and continues through valve gap 103 and into filter chamber housing 110 through outlet tube member 114.

After passing through the disc filter elements 150, the respective two filtered liquid streams combine through the outlet T-or Y-shaped flow combiner 190 and exit the dual unit 100 through the outlet 191e of the flow combiner 190.

An electronic controller (not shown) is configured to periodically initiate a backwash process (one at a time) for cleaning the filter elements 150 as desired by a user or based on monitoring the operation of the dual unit 100: operation of the dual unit 100 is monitored either as a function of the cumulative amount of filtered liquid measured since the last flushing procedure, the total number of operating hours after a previously performed cleaning procedure, or as a function of the pressure level dropping below a predetermined threshold corresponding to the degree of filter clogging due to accumulated dirt.

After the controller initiates the cleaning process, the piston 134 is pushed (by fluid forced into the control port 131 from an external pressurized source triggered by the controller) to drive the plug 136 forward toward the inlet opening. At the same time, the disc filter element 150 is switched into its backflush mode of operation with a predetermined delay or with a pressure-dependent time delay. In some exemplary embodiments, the switch to the backwash mode of operation may be accomplished using a change in the hydraulic pressure differential across the hydraulic switch of the filter element 150 caused by a change in the position of the common valve plug 136 (or, for example, in various other embodiments, by forcing fluid into its control port 155 from an external pressurized source triggered by the controller). Thus, the tray cup 151 moves away from the tray, allowing them to be separated for cleaning. In some embodiments, the controller is programmed to delay switching the disc filter 150 to the cleaning mode until the inlet opening is completely or almost sealed by the plug 136. Such a delay is desirable, for example, to ensure that the direction of flow through the filter is reversed when the separation discs are allowed to clean. In embodiments in which the disc filter 150 is switched between a filtering mode of operation and a cleaning mode, the desired delay in the transition to the cleaning mode may be achieved by a suitable design of the hydraulic actuator of the disc filter and of the switching flow through the valve during the transition of the valve from the filtering position to the reverse flow position. As indicated by the dashed arrows in fig. 1B, as long as the inlet opening of the valve in the filter assembly being cleaned is largely, if not completely, open, no reverse flow through the disc filter 150 can be guaranteed. This is because the pressure of the liquid communicating directly from the external liquid source to the disc filter 150 through the outlet tube member 114 (of the cleaned filter assembly) may be greater than the pressure of the liquid communicating through the filter chambers of the mirror image filter assembly. The necessity of a delay between activation of the valve and activation of the disc filter and, if a delay is required, the duration of the delay can be determined separately in each filtration project and the controller can be programmed accordingly based on experience gained in other projects or based on field experiments (in some embodiments, the hydraulic actuator and the valve can be designed accordingly).

During the final phase of the plug transition to its forwardmost position, the front protrusion 136F in the front wall of the valve accelerates the decrease of the accessibility of the inlet opening to the incoming flow, thereby minimizing the liquid loss through the drain port, accelerating the pressure reversal over the disc filter, allowing to shorten the delay and to switch the disc filter to the cleaning mode more quickly.

Fig. 1B illustrates some stages during the transition state of the dual cell 100 from the filtration-only mode of operation to the cleaning mode of operation. The rear projection 136R of the plug 136 is shown fully withdrawn from the cylindrical recess 104h with a significant gap therebetween. At this stage, liquid can escape freely from the valve's void 103 into the cylindrical recess 104h, as indicated by the small arrow near the rear projection 136R, and exit the left side unit through the drain outlet 103c and the drain tube segment 132. Depending on the degree of overlap between the cylindrical wall relating to the rear projection 136R and the inner cylindrical wall constituting the cylindrical recess 104h, and depending on the mutual cooperation relating to them, the escape of liquid from the interspace 103 to the discharge outlet 103c can start immediately after the start of the cleaning process and as soon as the plug 136 leaves its final hermetically sealed position. For example, in some embodiments, at least one of the cylindrical wall of the rear protrusion 136R and the inner cylindrical wall of the recessed liner 104 is provided with a gasket (e.g., an annular gasket 137 near the rear end of the rear protrusion 136R of the plug, see fig. 1D, and an annular gasket 138 near the opening of the plug facing the recessed liner 104, see fig. 1B) for sealing between the rear extension and the recess, as long as the rear extension is not completely withdrawn from the recess. In some embodiments, the gasket 137 of fig. 1D may be sleeve-like, i.e., extend over a particular portion (up to 100%) of the length of the rear protrusion 136R. In embodiments implementing a gasket for sealing the gap between the outer cylindrical wall of the rear protrusion 136R and the inner cylindrical wall of the cylindrical recess 104h, the escape of liquid only begins to occur when the rear extension is completely (or almost completely) separated from the recess. In other embodiments, the cylindrical walls may be configured to constantly have some small clearance therebetween to minimize or completely avoid friction between the plugs during their transition from one mode of operation to another. In such an embodiment, a small leak may begin immediately upon separation of the plug 136 from its rearmost position through the gap, then gradually withdraw from the cylindrical recess 104h due to the rear projection 136R in the first stage of the transition, and gradually increase, but not significantly, due to the gradually increasing spacing between the cylindrical recess 104h and the remote rear projection 136R in the middle stage of the transition. Since the conical rear projection 136R has already passed through the inlet opening in the intermediate and later stages of the transition state, the incoming flow is increasingly restricted and the total liquid waste is still small.

In various embodiments of the presently disclosed subject matter, the distance between the front end 136FF of the front projection 136F and the rear end 136RR of the rear projection 136R is equal to or greater than the distance between the front end of the cylindrical recess 104h (which is the end of the cylindrical recess 104h closer to the outer opening) and the outer opening. In some embodiments, the distance is greater than 80% of the distance between the front end of the recess and the outer opening, but shorter than the distance between the front end of the recess and the outer opening.

In some embodiments of the disclosed subject matter, the rear projection 136R occupies the volume of the recess or the front projection 136F passes through the external opening for at least 50% of the full range of linear motion of the stopper between the first and second extreme positions.

Experiments conducted with embodiments implementing the solution according to the disclosed subject matter show that the water wasted in a typical automatic cleaning process is significantly reduced compared to a similar system lacking the proposed solution.

When the plug 136 is in its forwardmost position as illustrated in fig. 1C, an effective flushing flow will occur during steady state of the cleaning process. Since the valve openings of the left filter assembly are blocked by the corresponding plugs 136, all of the pressure of the supplied liquid will fall on the right filter assembly, thereby increasing the flow through the filter elements of the right filter assembly, while utilizing the increased diameter of the right tube section 181R (which is equal to the diameter of the inlet tube section 181), the gently arched design, and the uninterrupted, non-tortuous flow path along the entire liquid path between the inlet openings and the filter elements 150.

Thus, the liquid flow at the outlet of the left filter chamber will be sufficient to supply an effective reverse flow through the filter chambers of the left assembly as required for backwash, while continuing to supply filtered liquid to the main line, as indicated by the arrows shown in the flow combiner 190 (acting as a flow splitter during cleaning of the mirrored filter assemblies).

In some embodiments of the disclosed subject matter, backwashing of two mirrored filter assemblies may occur simultaneously upon user activation or as a routine process. In such an embodiment, the backwash process would be activated simultaneously by simultaneously controlling both plugs 136 to close the inlet openings and by providing a reverse flow of liquid from the external pressurized liquid source through outlet 191e of flow combiner 190 into flow combiner 190. Once the rear projections 136R of the two plugs are withdrawn from their cylindrical recesses 104h, the pressurized reverse fluid flow will be split into the left and

right filter elements

150, 150 by the left and

right tube segments

191L, 191R, respectively.

In some embodiments, the flow combiner 190 is integral with the body of the chamber housing 110 of the left and right chambers. In various embodiments, each chamber housing 110 has an open proximal end 112 facing the open proximal end 112 of its counterpart chamber housing 110 (see fig. 1E), the left and

right spool pieces

191L, 191R of the chamber housing 110 and the flow combiner 190, respectively, are configured to be coupled by a coupling clamp, allowing the flow combiner to be secured to the duplex unit 100 with the longitudinal axis of the center spool piece 191 of the flow combiner 190 at any desired angle to the plane of the figure (except for the angle where it is further rotated to be blocked by the body of other components (e.g., the body of the flow splitter 180)).

In some embodiments, the flow splitter 180 is integral with the body of the left and right valves (which are similar to the common valve 102). In various embodiments, the common valve 102 and the left and

right tube sections

181L, 181R of the flow splitter 180 are configured to be coupled by coupling clamps, respectively, allowing the flow splitter to be secured to the twin unit 100 with the longitudinal axis of the center tube section 181 of the flow splitter at any desired angle to the plane of the drawing (except for the angle where it is further rotated while blocked by the body of other components (e.g., the body of the flow combiner 190)).

In various embodiments of the disclosed subject matter in which the flow splitter 180 and flow combiner 190 are tiltable and thus can each be fixed facing a desired direction, the twin cell 100 becomes highly versatile and can be suitably integrated into different main line architectures, including but not limited to the L, Z, I and U relationship between the entering and exiting portions of the main line (where the letter shaped ends are aligned with the longitudinal axes of the entering and exiting main line portions).

In various embodiments of the disclosed subject matter, either of the Y-splitter 180 and the Y-combiner 190 can further include at least one integral multi-function port for removably connecting desired accessories, such as air valves, pressure gauges, turbidity sensors, auxiliary filters, and the like.

The versatility gained by providing the tilting capability between either of the Y-splitter 180 and the Y-combiner 190 and the single-piece unit 101 further facilitates stacking multiple mirror-imaged units together into a compact and well-organized pack of automatic backwash filter units.

When the term "about" is used in connection with a stated dimension, size, quantity, measurement, etc., a deviation of up to 10% is contemplated unless specifically stated otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosed subject matter. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the disclosed subject matter has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosed subject matter in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosed subject matter. The embodiments were chosen and described in order to best explain the principles of the disclosed subject matter and the practical application, and to enable others of ordinary skill in the art to understand the disclosed subject matter for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. A filtration system comprising:

a filtration chamber;

a filter element housed within the filter chamber, wherein the filter element comprises a body of the filter element;

a common valve, the common valve comprising:

a valve housing in fluid communication with the filtration chamber, a source of fluid to be filtered, and a discharge port for backwash fluid through three respective openings in the valve housing, and

a movable plug for selecting between a first flow path and a second flow path, wherein the movable plug is movable within a central void of the common valve between a first extreme position and a second extreme position of the movable plug, wherein the first extreme position is associated with a filtration mode of operation corresponding to the first flow path, wherein the second extreme position is associated with a backwash mode of operation corresponding to the second flow path, and

a length of tubing connected between the filtration chamber and the common valve,

wherein the common valve, the filter chamber and the tube segment are collectively configured for: providing an uninterrupted, tortuosity-free flow channel extending at least from outside an inlet opening of the common valve to the body of the filter element whenever the common valve is in the filtering mode of operation,

wherein the movable plug is linearly movable within the central void of the common valve,

wherein the rear wall of the movable plug has a protrusion that fits within a mating retaining recess,

wherein the mating fixing recess extends between a discharge outlet formed in a wall of the valve housing and the central void and has an internal free space with a predetermined volume, wherein the protrusion is configured to at least partially occupy the internal free space as the movable plug transitions between a rearmost position of the movable plug within the central void and a position closer to a forwardmost position of the movable plug within the central void until the protrusion is fully clear of the mating securing recess, thereby reducing fluid drainage through the mating fixed recess during transition of the movable plug between a filtration mode of operation and a backwash mode of operation depending on the extent to which the volume of the mating fixed recess is occupied by the rear projection.

2. A filtration system according to claim 1, wherein the non-tortuous flow passage has a cross-sectional area perpendicular to its longitudinal axis that is 50% or more of the area of the inlet opening of the common valve.

3. The filtration system of claim 1, wherein the movable plug is linearly movable between the first limit position and the second limit position, wherein the movable plug includes a rear protrusion, wherein the rear protrusion is configured to restrict passage of fluid from the central void of the common valve to the drain port during linear movement of the movable plug from the first limit position to the second limit position, wherein for at least a first 30% of a full extent of the linear movement, at least a portion of a predetermined volume of the mating fixed recess is occupied by the rear protrusion, thereby reducing fluid waste through the drain port according to a degree of the volume of the mating fixed recess occupied by the rear protrusion.

4. The filtration system of claim 3, wherein the rear protrusion is cylindrical, a height of the rear protrusion being oriented parallel to the direction of linear motion.

5. The filtration system of claim 1, wherein the movable plug is linearly movable between the first limit position and the second limit position, wherein the movable plug includes a front protrusion configured to enter the inlet opening to reduce a flow rate of fluid entering the inlet opening during linear movement of the movable plug from the first limit position to the second limit position, wherein for at least a last 30% of a full stroke of the linear movement, at least a portion of the front protrusion passes through the inlet opening to reduce fluid waste through the drain port as a function of a degree to which the front protrusion passes through the inlet opening.

6. The filtration system of claim 5, wherein the front protrusion is tapered, tapering toward the inlet opening.

7. The filtration system of claim 1, wherein the angle between the longitudinal axis of the tube segment and the longitudinal axis of the filtration chamber is 35 to 55 degrees.

8. The filtration system of claim 1, wherein the tube segment has an elliptical cross-section perpendicular to its longitudinal axis, and the elliptical cross-section is flat in a direction parallel to the direction of linear motion, such that for a given cross-sectional area of the tube segment, the range of linear motion of the movable plug is shortened.

9. The filtration system of claim 1, wherein the proximal end of the filtration chamber, at least a majority of the valve housing of the common valve, and the tube segment are inseparable members of a single piece of material.

10. The filtration system of claim 1, wherein flow through a first opening in the housing of the filtration chamber enters the chamber during a filtration mode of operation and exits the chamber during a backwash mode of operation, wherein flow through a second opening in the housing of the filtration chamber exits the chamber during a filtration mode of operation and enters the chamber during a backwash mode of operation.

11. A dual filtration system comprising a first filtration system and a second filtration system, each of the filtration systems of claim 1, connected together in a mirror image configuration, wherein the inlet opening of the common valve in the first filtration system faces the inlet opening of the common valve in the second filtration system and is aligned with the inlet opening of the common valve in the second filtration system by a flow splitter for fluid to be filtered.

12. The dual filtration system of claim 11, wherein the flow splitter comprises a pair of arcuate tubes diverging from a central common tube.

13. A dual filtration system comprising a first filtration system and a second filtration system, each of the filtration systems of claim 1, connected together in a mirror image configuration, wherein the outlet openings of the filtration chambers in the first filtration system face the outlet openings of the filtration chambers in the second filtration system and are aligned with the outlet openings of the filtration chambers in the second filtration system by a flow combiner of filtered fluid.

14. The dual filtration system of claim 13, wherein the flow combiner comprises a pair of arcuate tubes diverging from a central common tube.

15. The dual filtration system of claim 14, wherein the maximum inner bend radius of each of the pair of arcuate tubes is 100% to 150% of the diameter of the central common tube.

16. The dual filtration system of claim 14, wherein the central common tube of flow splitter has an internal cross-sectional area equal to an internal cross-sectional area of any one of the pair of arcuate tubes diverging therefrom.

17. The dual filtration system of claim 14, wherein the flow combiner's central common tube has an inner cross-sectional area equal to an inner cross-sectional area of any one of the pair of arcuate tubes that diverge from the central common tube.

18. A valve device for a filtration system according to claim 1, comprising:

a linearly movable stopper for selecting between a first flow path and a second flow path corresponding to a first limit position and a second limit position of the linearly movable stopper, and constituting a common valve,

a housing within which a linearly movable stopper is linearly movable between the first and second extreme positions;

a normally-open port common to the first flow path and the second flow path;

a first port having an external opening in fluid communication with the normally open port when the linearly movable plug is in the first limit position;

a second port in fluid communication with the normally open port when the linearly movable plug is in the second extreme position;

wherein when the linearly movable plug is in the first limit position, the fluid communication between the external opening and the normally-open port comprises a linear flow path having a cross-sectional area greater than 50% of the area of the external opening, constituting an uninterrupted unbent flow path at least from the exterior of the external opening to the exterior of the normally-open port.

19. The valve device of claim 18, wherein the cross-sectional area of the linear flow path is greater than 75% of the area of the external opening.

20. The valve device of claim 18, wherein said normally open port has a predetermined open area in a plane parallel to a direction of linear movement of said linearly movable plug, wherein said open area has a minor axis in said plane defining a width of a bidirectional port and a major axis in said plane defining a length of said bidirectional port, wherein said width is less than said length, wherein said minor axis in said plane and said width of the respective bidirectional port are parallel to said direction of movement of said linearly movable plug.

21. The valve apparatus of claim 18, wherein a rear wall of the linearly movable plug has a protrusion that fits within a mating fixed recess, wherein the mating fixed recess extends between the second port and a central void of the valve apparatus, wherein the protrusion is configured to prevent or restrict the flow of fluid from the central void to the second port when the linearly movable plug transitions between a rearmost position within the void, which may be associated with a filtration mode of operation of a self-cleaning filtration system, and a position adjacent to a forwardmost position thereof within the void, which may be associated with a backwash mode of operation of the self-cleaning filtration system, such that during a change mode of operation of the linearly movable plug once configured from the filtration mode of operation to the backwash mode of operation, allowing for reduced liquid discharge.

22. The valve arrangement of claim 18, wherein the first extreme position is associable with a filtering mode of operation of a self-cleaning filtering system, wherein the second extreme position is associated with a back-flushing mode of operation of the self-cleaning filtration system, wherein the linearly movable stopper comprises a front protrusion configured to enter the external opening, such that for at least the last 30% of the full linear movement of the linearly movable stopper between the first and second extreme positions, reducing the flow of fluid into the first port during linear movement of the linearly movable plug from the first extreme position to the second extreme position, thereby reducing fluid from being wasted through the second port depending on the extent to which the front projection penetrates the outer opening.

23. The valve device according to claim 18,

wherein a rear wall of the linearly movable plug has a protrusion that fits within a mating retaining recess extending between the second port and a central void of the valve device, wherein the protrusion is configured to block or restrict fluid flow from the central void to the second port during transition of the linearly movable plug between a rearmost position within the void and a forwardmost position adjacent thereto within the void;

wherein the linearly movable stopper further comprises a front protrusion configured to enter the external opening to reduce a flow of fluid into the first port during linear movement of the linearly movable stopper from the first extreme position to the second extreme position for at least a last 30% of a full linear movement of the linearly movable stopper between the first extreme position and the second extreme position; and is

Wherein the rearmost position is associable with a filter mode of operation of a self-cleaning filter system, wherein the frontmost position is associable with a backwash mode of operation of the self-cleaning filter system, thereby allowing for reduced liquid drainage depending on the extent to which the volume of the matching fixed recess is occupied by a rear projection and the extent to which the front projection passes through the external opening during a change mode of operation of the linearly movable plug once configured from the filter mode of operation to the backwash mode of operation.

24. The valve device of claim 23, wherein the rear protrusion occupies the volume of the mating retaining recess or the front protrusion penetrates the exterior opening for at least 50% of the full extent of linear movement of the linearly movable plug between the first and second extreme positions.

25. The valve device of claim 23, wherein a distance between a front end of the front projection and a rear end of the rear projection is greater than 80% of a distance between a front end of the mating retaining recess and the exterior opening.

26. The valve device of claim 23, wherein a distance between a front end of the front protrusion and a rear end of the rear protrusion is equal to or greater than a distance between a front end of the mating retaining recess and the exterior opening.

27. A filtration system component for a filtration system according to claim 1, comprising in an inseparable single piece: a portion of the filtration chamber housing, a portion of the common valve housing exterior to and remote from the portion of the filtration chamber housing, and a tube segment connected between the portion of the filtration chamber housing and the portion of the common valve housing, wherein the portion of the filtration chamber housing, the portion of the common valve housing, and the tube segment are collectively configured for: providing an uninterrupted unbent fluid passage extending at least from an exterior of an inlet opening of the common valve to an interior of a portion of the filtration chamber housing.